Abstract

To meet the formal requirements for the collection, interpretation and analysis ofenvironmental baseline data in Australia's
offshore areas in which further petroleumexploration could take place, the modern geological processes, Quaternary evolutionand
environmental features of the potential release area(s) in the Van Diemen Rise(East Malita Graben, Timor Sea) which will be
included in the first release of 1992are described, analysed and interpreted.
The potential release area(s) overlie part of the Van Diemen Rise in the eastern partof the Timor Sea in the vicinity of Cootamundra
and Evans Shoals. Sea bottomsediments in the region are dominantly calcareous sand grade and derived from thebreakdown of
skeletal material which has developed on an extensive number ofbanks and shoals which characterise this part of the continental
shelf.
The sea bottom is also marked by a number of sinuous and narrow curvilinearchannel like features which along with other geomorphic
elements are attributed tothe effects of subaerial exposure and weathering of the carbonate shelf sedimentwedge during Quaternary
lower sea level stages, as well as marine and coastalprocesses which occurred during sea level rise and marine inundation.
The Holocene rise in sea level has resulted in inundation of a large number of wave-cut scarps, channels and flat top banks,
the latter of which became the focus ofcarbonate reef growth and hence a source of much of the sand-grade carbonatesediments
evident on the sea floor.